750 m summit in Eryri (Snowdonia). 8 forecast days covering wind, cloud, rain and temperature, updated 5 November 2026 at 16:25 UTC.
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Confidence: Medium
Overall hill weather66Mixed
Summit wind · 08:00-17:0015-30 mph easterlySummit gusts · 08:00-17:0035-45 mphFeels like-6 to -2°CPrecipitationLittle or noneCloud-free summit estimate85%Cloud base through day700-1,500 mFreezing levelAbove summitDaylightSunrise 07:19 · Sunset 16:38 · 9.3 hours daylight
The day on the hill
A mixed day on Diffwys, with a blustery wind.
Wind
On the summit expect an easterly wind of 15–30 mph for most of the day, with gusts of 35–45 mph at the windiest. Lower down on the open hillside it will be more like 10–20 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on ridges and edges.
Cloud and visibility
The tops should stay mostly clear of cloud. A few forecast models bring the cloud base down to around 600–900 m at times. The cloud base sits close to summit height, so the top could go in and out of cloud at short notice. The air should be clear, so expect far-reaching views as long as the tops stay clear.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 2 to 6°C, feeling like -6 to -2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:40pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
There is some disagreement between forecast models on wind strength. Things could still change through the day, so keep an eye on the sky.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 3.3 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 20-30 mph. Gusts around 35-45 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges.
60
Afternoon · 12:00–17:00
GoodSummit winds around 15-30 mph. Gusts around 30-40 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges. Summit cloud becomes more persistent later.
71
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the cold: gusts of about 25 mph.59Mixed · 600 mView detailsHide details
Night beginning Thursday 5 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the cold. Gusts reach about 25 mph on open ground, so peg out well and use the guylines. Look for shelter from the east. It should stay dry. Overnight lows of about 3°C at 300 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 5 Nov, 17:00 GMT to 6 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
13 mph / 21 mph
Typical / low
3.9°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m59 · mixed
Wind / gust
16 mph / 25 mph
Typical / low
3.9°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
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Daytime · exposed rockClimbing & scramblingBetaFair conditions for exposed scrambling: gusts of 35–45 mph.Mixed69View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Fair conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Gusts of 35–45 mph could throw you off balance on exposed moves and ridges. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceProbably dryPeak gust35-45 mphRain0.0 mm
Main concerngusts of 35–45 mph
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Thursday 5 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
A fine day on Diffwys: dry, with light winds and clear tops for most of the day.
Wind
On the summit expect a south-easterly wind of 5–20 mph for most of the day, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.
Rain and ground
Mostly dry, but some forecast models bring rain in the morning.
Warmth and kit
On the tops it will be around 2 to 6°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Some of the detail could still change, so have a last look at the forecast in the morning before you set off.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 4.7 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
GoodSummit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is possible during the morning, but forecast models disagree on whether it will fall.
82
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
90
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA very good night for a wild camp: dry, with light winds.91Excellent · 600 mView detailsHide details
Night beginning Friday 6 November 2026
Full overnight outlook
A very good night for a wild camp. Light winds on open ground, gusting no more than about 11 mph. It should stay dry. Overnight lows of about 6°C at 300 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 6 Nov, 17:00 GMT to 7 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m91 · very good
Wind / gust
4 mph / 10 mph
Typical / low
5.9°C / 5.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m91 · very good
Wind / gust
5 mph / 11 mph
Typical / low
5.9°C / 5.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Good conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceDry initially; rain possiblePeak gust15-25 mphRainPossible · 42%
Main concernrain possible despite mostly dry conditions being favoured
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Friday 6 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-10 mph northwesterlySummit gusts · 08:00-17:005-15 mphFeels like-4 to 0°CPrecipitationLittle or noneCloud-free summit estimate85%Cloud base through day600-1,400 mFreezing levelAbove summitDaylightSunrise 07:23 · Sunset 16:35 · 9.2 hours daylight
The day on the hill
A fine day on Diffwys: dry, with light winds and clear tops for most of the day.
Wind
On the summit expect light winds of up to 10 mph, mainly north-westerly, with gusts of 5–15 mph at the windiest.
Cloud and visibility
The tops should stay mostly clear of cloud. The cloud base could be as low as 600–900 m mid-afternoon. Patchy mist is possible in sheltered valleys early on. Good spells of sunshine are likely. The air should be clear, so expect far-reaching views as long as the tops stay clear.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still two days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 6.9 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
90
Afternoon · 12:00–17:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud becomes more persistent later.
89
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of damp air: gusts of about 10 mph.54Mixed · 600 mView detailsHide details
Night beginning Saturday 7 November 2026
Full overnight outlook
A mixed night to camp, mainly because of damp air. Light winds on open ground, gusting no more than about 10 mph. Dry to pitch, then a little rain overnight, easing by morning, though the tent may still be wet. Up around 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp at every height we checked (300-600 m), so expect heavy condensation. Leave the vents open. Overnight lows of about 4°C at 300 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 7 Nov, 17:00 GMT to 8 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
4 mph / 8 mph
Typical / low
4.8°C / 4.5°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m54 · mixed
Wind / gust
5 mph / 10 mph
Typical / low
4.6°C / 4.5°C · much of the night
In cloud
60% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceProbably dryPeak gust5-15 mphRain0.0 mm
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Saturday 7 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-10 mph southwesterlySummit gusts · 08:00-17:005-15 mphFeels like-2 to 2°CPrecipitationLittle or noneCloud-free summit estimate50%Cloud base through day500-800 mFreezing levelAbove summitDaylightSunrise 07:25 · Sunset 16:33 · 9.1 hours daylight
The day on the hill
A good day on Diffwys: dry, with light winds.
Wind
On the summit expect light winds of up to 10 mph, mainly south-westerly, with gusts of 5–15 mph at the windiest. Lower down on the open hillside the wind will be light, under 5 mph.
Cloud and visibility
Cloud on the tops early should lift off them by early afternoon. The cloud base could be as low as 500–800 m in the early afternoon. Mist or fog is possible in the valleys early on, clearing by about 10am.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -2 to 2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud heights are particularly hard to pin down today. It's still three days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 1.9 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
66
Afternoon · 12:00–17:00
ExcellentSummit winds around 0-10 mph. Gusts around 0-10 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
86
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the cold: dry, with light winds.59Mixed · 600 mView detailsHide details
Night beginning Sunday 8 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the cold. Light winds on open ground, gusting no more than about 20 mph. It should stay dry. A cold night, down to about 1°C around 600 m. A warm 3-season or 3–4 season bag rated to about -2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about -2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Fair conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceProbably dryPeak gust5-15 mphRain0.0 mm
Main concernmuch of the route may be in cloud
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Sunday 8 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:0020-35 mph southeasterlySummit gusts · 08:00-17:0030-40 mphFeels like-6 to -2°CPrecipitationLittle or noneCloud-free summit estimate85%Cloud base through day500-1,300 mFreezing level600-900 mDaylightSunrise 07:27 · Sunset 16:31 · 9.1 hours daylight
The day on the hill
A mixed day on Diffwys, with a blustery wind.
Wind
On the summit expect a south-easterly wind of 20–35 mph for most of the day, with gusts of 30–40 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on ridges and edges. If the windier forecast models are right, summit gusts could reach 60–70 mph.
Cloud and visibility
The tops should stay mostly clear of cloud. The cloud base could be as low as 500–800 m mid-morning. Mist or fog is possible in the valleys early on, clearing by about 4am. Good spells of sunshine are likely.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -6 to -2°C in the wind. The freezing level is close to summit height. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still four days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 7.7 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 20-30 mph. Gusts around 30-40 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges.
62
Afternoon · 12:00–17:00
MixedSummit winds around 25-35 mph. Gusts around 30-40 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges.
59
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch up around 600 m (gusts of about 40 mph). Lower down, a poor night to camp on open ground.19Poor · 600 mView detailsHide details
Night beginning Monday 9 November 2026
Full overnight outlook
Too windy for an exposed pitch up around 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 40 mph on open ground, which makes for a noisy, testing night even in a good tent. Pitch low down and in real shelter, or leave it for another night. Dry to pitch, then some light rain overnight and into the morning, so expect to pack a wet tent. Up around 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 3°C around 300 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaFair conditions for exposed scrambling: gusts of 30–40 mph.Mixed64View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Fair conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. Gusts of 30–40 mph could throw you off balance on exposed moves and ridges. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceDry initially; rain possiblePeak gust30-40 mphRainPossible · 25%
Main factorsgusts of 30–40 mphrain possible despite mostly dry conditions being favoured
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Monday 9 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:0020-35 mph southeasterlySummit gusts · 08:00-17:0040-50 mphFeels like-6 to -2°CPrecipitationUp to around 2 mmCloud-free summit estimate50%Cloud base through day600-2,700 mFreezing levelAbove summitDaylightSunrise 07:28 · Sunset 16:29 · 9.0 hours daylight
The day on the hill
A poor day on the tops of Diffwys, with strong, gusty winds.
Wind
On the summit expect a south-easterly wind of around 30–40 mph first thing, easing to 15–25 mph by mid-afternoon, with gusts of 40–50 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to knock you off balance, so take care near edges and on narrow ridges. If the windier forecast models are right, summit gusts could reach 70–80 mph.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit early in the morning. A few forecast models bring the cloud base down to around 400–700 m at times. The cloud base sits close to summit height, so the top could go in and out of cloud at short notice.
Rain and ground
Drizzle for much of the day. Some forecast models keep it drier in the morning.
Warmth and kit
On the tops it will be around 2 to 6°C, feeling like -6 to -2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
There is some disagreement between forecast models on wind strength. It's still five days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 5.2 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
PoorSummit winds around 25-35 mph. Gusts around 40-50 mph are possible on exposed ground. Gusts this strong can knock you off balance, so take care near edges and on narrow ridges. Rain is forecast during this period. Rain is possible during the morning, but forecast models disagree on whether it will fall.
46
Afternoon · 12:00–17:00
PoorWinds ease compared with the morning. Summit winds around 20-30 mph. Gusts around 30-40 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
43
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the rain: about 4 mm of rain.54Mixed · 600 mView detailsHide details
Night beginning Tuesday 10 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the rain. Gusts reach about 25 mph on open ground, so peg out well and use the guylines. Look for shelter from the south. Expect about 4 mm of rain, with rain while you pitch and still falling when you pack up. Up around 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. Overnight lows of about 8°C at 300 m. A 3-season bag rated to about 6°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 40–50 mph.Poor0View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 40–50 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceWet rock likelyPeak gust40-50 mphRain2.7 mm
Main factorsgusts of 40–50 mphwet rock likelymuch of the route may be in cloud
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Tuesday 10 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
A mixed day on Diffwys, with rain for much of the day and cloud coming and going on the summit.
Wind
On the summit expect a southerly wind of 5–20 mph for most of the day, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
Expect the summit to be in cloud for most of the day. The cloud base could be as low as 400–700 m mid-afternoon. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.
Rain and ground
Rain for much of the day, becoming heavier later. Expect 5–10 mm in total. Some forecast models keep it drier in the afternoon.
Warmth and kit
On the tops it will be around 6 to 10°C, feeling like 2 to 6°C in the wind. The freezing level is above the summits. A windproof and an extra layer for stops will help. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still six days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is forecast during this period.
57
Afternoon · 12:00–17:00
MixedMore rain is expected. Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
52
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the rain: about 8 mm of rain.59Mixed · 600 mView detailsHide details
Night beginning Wednesday 11 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the rain. Light winds on open ground, gusting no more than about 20 mph. Expect about 8 mm of rain, mostly early on, so you'll likely pitch in the rain. Up around 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. Overnight lows of about 7°C at 300 m. A 3-season bag rated to about 4°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 4°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceWet rock likelyPeak gust15-25 mphRain12.4 mm
Main factorswet rock likelymuch of the route may be in cloud
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Wednesday 11 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-15 mph northeasterlySummit gusts · 08:00-17:0010-20 mphFeels like-4 to 0°CPrecipitationUp to around 2 mmCloud-free summit estimate50%Cloud base through day800-1,400 mFreezing levelAbove summitDaylightSunrise 07:32 · Sunset 16:26 · 8.9 hours daylight
The day on the hill
A fine day on Diffwys: light winds.
Wind
On the summit expect light winds of up to 15 mph, mainly north-easterly, with gusts of 10–20 mph at the windiest.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit mid-morning. The cloud base sits close to summit height, so the top could go in and out of cloud at short notice.
Rain and ground
Drizzle sets in during the early afternoon. It will be wet underfoot after recent rain.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still seven days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
GoodSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
83
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
92
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA poor night to camp on open ground: a frost, down to 0°C.39Poor · 600 mView detailsHide details
Night beginning Thursday 12 November 2026
Full overnight outlook
A poor night to camp on open ground. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the northeast. It should stay dry. A frost at every height we checked (300-600 m), down to about 0°C. A warm 3-season or 3–4 season bag rated to about -4°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 12 Nov, 17:00 GMT to 13 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m39 · poor
Wind / gust
14 mph / 24 mph
Typical / low
-0.1°C / -0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m39 · poor
Wind / gust
16 mph / 29 mph
Typical / low
-0.1°C / -0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about -4°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Mixed conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. The rock around the summit is mostly mudstone or slate, a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceWet rock likelyPeak gust10-20 mphRain0.6 mm
Main concernwet rock likely
Representative rock around the summit
Mudstone and siltstoneGamlan Formation
Origin
Sedimentary
Broad rock-response group
Slate or mudstone
Mapping
BGS Geology 50K · 1:50,000
Summit area
Slate or mudstone in 82% of 17 BGS samples within 350 m
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Geological detail and BGS records
Mapped variation
3 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Summit-area sample
Mudstone and siltstoneGamlan Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS record →
Summit-area sample
Sandstone and mudstoneBarmouth Formation
Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS record →
Summit-area sample
MudstoneHafotty Formation
Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Diffwys on Thursday 12 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
